In Canadian patent No. 767,004 issued Sep. 12, 1967 to the present inventor, a locking device for scaffolding is described and claimed. In this patent, two stay rods 21 are held in position by their bored ends on a stem 9 projecting in the interior plane of each scaffolding frame, by a locking device having a single latch 14 pivoted at one end to the free end of an arm 11 secured to the frame above the stem 9 and extending parallel thereto. The upper end 20 of a short curved stem 18 being secured to the back of latch 14, extends through arm 11, wherein latch 14 may be lifted by pulling end 20.
Latch 14 holds in position the two stay rods 21, in its lowered limit position shown in FIG. 1, thus preventing not only release from stem 9 but also preventing wobbling following vibrations generated by a worker walking over a panel supported by this scaffolding.
One disadvantage of this device, is that the latch is not destined to hold in position a variable number of stay rods, e.g. a single one, since, then, the end bore of the stay rod could be widened with wear induced by the vibrations when the stay rod wobbles on the stem, or three stay rods, when interconnected superimposed frames are used, since then, no gap will be available for the third end of stay rod.